From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5F7C1C43441 for ; Wed, 21 Nov 2018 18:59:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2CDED214D9 for ; Wed, 21 Nov 2018 18:59:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2CDED214D9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731763AbeKVFe6 (ORCPT ); Thu, 22 Nov 2018 00:34:58 -0500 Received: from mga01.intel.com ([192.55.52.88]:48953 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731709AbeKVFe5 (ORCPT ); Thu, 22 Nov 2018 00:34:57 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 21 Nov 2018 10:59:25 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,262,1539673200"; d="scan'208";a="91115379" Received: from schen9-desk.jf.intel.com (HELO [10.54.74.144]) ([10.54.74.144]) by orsmga007.jf.intel.com with ESMTP; 21 Nov 2018 10:59:25 -0800 Subject: Re: [PATCH 4.19 041/361] x86/speculation: Enable cross-hyperthread spectre v2 STIBP mitigation To: Jiri Kosina Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, stable@vger.kernel.org, Thomas Gleixner , Peter Zijlstra , Josh Poimboeuf , Andrea Arcangeli , WoodhouseDavid , Andi Kleen , SchauflerCasey , Dave Stewart References: <20181111221619.915519183@linuxfoundation.org> <20181111221625.598298393@linuxfoundation.org> <20181121135611.GA26411@kroah.com> <41234d20-294f-d0f4-336c-64bf9fcb92a7@linux.intel.com> From: Tim Chen Openpgp: preference=signencrypt Autocrypt: addr=tim.c.chen@linux.intel.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/21/2018 10:21 AM, Jiri Kosina wrote: > On Wed, 21 Nov 2018, Tim Chen wrote: > >>> Is it reverted in Linus's tree? If not, then anything that comes "later >>> on" will not apply here, right? >>> >>> I see the thread asking about this, but I got really conflicting >>> messages here, and now it's in all of the latest releases, and no >>> testing seems to have uncovered issues. Is it just a "slow down" >>> problem? >> >> Greg, >> >> It could be a big slow down in excess of 20% for some applications. >> And cross sibling Spectre v2 attack is quite hard to pull off. >> >> So till we have the accompanying patchset that only apply STIBP on processes >> that really need it instead of universally, it should be withheld from >> stable. > > Agreed; it will be trivially reintroduced with the rest, once it's ready. > It's being built on top of that patch. > Thanks. Appreciate it. Tim